Total chlorine content (TCC) is an important quality parameter of refuse derived fuel (RDF) or biomass wastes due to boiler corrosion or ash slagging. These phenomena depend upon the organic or inorganic forms of chlorine (Cl) compounds combustion pathways. Present work investigates the TCC of RDF optimizing the Cl quantification procedure following standard oxygen bomb combustion. Hypochlorite (OCl-) ion was detected in different absorbing solutions (H2O; KOH; CO2-3/HCO3-) together with Cl-.A quantifying titration step was carried out in parallel to chloride quantification by ionic chromatography. TCC (sum of both Cl forms) of wheat straw and four different RDF were found to be 1.5 to 2 times higher than the content (0.6-1.6%) previously obtained, both in KOH 0.2 M. Similar TCC increase ratios were obtained for waste components. OCl- association with Cl-2 (g) formation during bomb calorimeter combustion is discussed. Further insight on RDF chlorine nature indicates that organic Cl should be the most relevant considering that its Cl is mostly non-soluble and releasable from fuel up to 850 degrees C. RDF or straw chlorinated emissions or gas phase corrosion are pointed out over ash slagging or fouling. However ash slagging may occur due to recombination of inorganic Cl. (C) 2014 Elsevier B.V. All rights reserved.